Exterior lamp structures are typically a molded plastic housing. Lamps vary in shape and size but all need to be securely attached and require features that aid alignment with the vehicle body to eliminate uneven or excessive gaps around the perimeter of the lamp. The vehicle body is typically a sheet metal structure with a pocket shaped to match that of the lamp structure for aerodynamics and styling.
When a lamp structure is inserted and securely attached to the vehicle body, it is highly desirable to have a precise and uniform fit around the perimeter of the lamp within the vehicle body pocket. Inside the vehicle body pocket are holes that are sized, shaped and positioned to receive studs, grommets or posts extending from the lamp structure for both alignment and secure attachment. If the sheet metal hole passes into an interior area of the vehicle, such as the trunk of a car, a gasket seal is typically used around the perimeter hole to prevent water or fumes from passing through the hole.
Examples of exterior vehicle lamp structures include but are not limited to head lamps, fog lamps, center high mounted stop lights and lamp assemblies. Exterior lamps often include multiple light functions. For instance, a lamp assembly often includes running, turn signal and backup lights in addition to the stop light.
Regardless of the type of exterior lamp arrangement, it is important to control lamp alignment with the vehicle body and have it well secured. Lamp alignment needs to be controlled with the vehicle body in all six directions in order to achieve a precise and uniform fit around the perimeter of the lamp structure. The six directions of lamp structure alignment that are needed with the vehicle body are right to left, up and down and fore and aft. Typically a combination of at least one alignment pin and at least one threaded grommet or threaded stud is used to both align and securely attach the lamp structure to the vehicle.
The efficiency of a vehicle assembly plant is a driving force behind product design since each assembly station is critically time dependent so not to be the bottle neck in the chain process. Eliminating the need to drive studs or nuts on the vehicle assembly line is highly desirable especially if the stud or nut is in a difficult to reach area inside the vehicle body with a stud or nut driver.